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Metal-catalyzed cross-coupling reactions are extensively employed in both academia and industry for the synthesis of biaryl derivatives for applications to both medicine and material science. Application of these methods to prepare tetra-ortho-substituted biaryls leads to chiral atropisomeric products that introduces the opportunity to use catalyst-control to develop asymmetric cross-coupling procedures to access these important compounds. Asymmetric Pd-catalyzed Suzuki-Miyaura and Negishi cross-coupling reactions to form tetra-ortho-substituted biaryls were studied employing a collection of P-chiral dihydrobenzooxaphosphole (BOP) and dihydrobenzoazaphosphole (BAP) ligands. Enantioselectivities of up to 95:5 and 85:15 er were identified for the Suzuki-Miyaura and Negishi cross-coupling reactions, respectively. Unique ligands for the Suzuki-Miyaura reaction vs the Negishi reaction were identified. A computational study on these Suzuki-Miyaura and Negishi cross-coupling reactions enabled an understanding in the differences between the enantiodiscriminating events between these two cross-coupling reactions. These results support that enantioselectivity in the Negishi reaction results from the reductive elimination step, whereas all steps in the Suzuki-Miyaura catalytic cycle contribute to the overall enantioselection with transmetalation and reductive elimination providing the most contribution to the observed selectivities.

The Pd-catalyzed 3-arylation of 2-oxindoles with aryl bromides, chlorides and triflates is found to proceed using i-Pr-BI-DIME and Me2-BI-DIME ligands. The mono-arylation of 3-unsubstituted oxindoles is accomplished using a Pd2(dba)3/i-Pr-BI-DIME catalyst system, and gives good yields of 3-aryloxindoles from aryl bromides and chlorides. The arylation of 3-substituted oxindoles is also possible using this catalyst/ligand system. The asymmetric arylation of 3-substituted oxindoles is accomplished using Me2-BI-DIME to furnish oxindoles bearing a quaternary C-3 stereocenter in enantiomeric ratios of up to 93:7.

Enantioselective synthesis of α-aryl and α-heteroaryl piperidines is reported. The key step is an iridium-catalyzed asymmetric hydrogenation of substituted N-benzyl pyridinium salts. High levels of enantioselectivity up to 99.3:0.7 er were obtained for a range of α-heteroaryl piperidines. DFT calculations support an outer-sphere dissociative mechanism for the pyridinium reduction. Notably, initial protonation of the final enamine intermediate determines the stereochemical outcome of the transformation rather than hydride reduction of the resultant iminium intermediate.

We report the synthesis and self-assembling properties of a new class of glucosyl triazole derivatives from glucose. The compounds are synthesized by a Cu(I) catalyzed azide/alkyne cycloaddition reaction, or the ‘click’ reaction. Several efficient low molecular weight organogelators were obtained in this study. We found that triazole analogs containing long alkyl hydroxyl groups and phenyl groups typically are effective in forming supramolecular gels.

A general, efficient, and highly diastereoselective method for the synthesis of structurally and sterically diverse P-chiral phosphine oxides was developed. The method relies on sequential nucleophilic substitution on the versatile chiral phosphinyl transfer agent 1,3,2-benzoxazaphosphinine-2-oxide, which features enhanced and differentiated P–N and P–O bond reactivity toward nucleophiles. The reactivities of both bonds are fine-tuned to allow cleavage to occur even with sterically hindered nucleophiles under mild conditions.

Described herein are the one-pot synthesis and characterization of a library of low molecular weight peptoid compounds that are able to form gels at room temperature. The compounds are synthesized from biologically-based starting materials, are biocompatible, and are resistant to degradation by proteases and peptidases. The compounds and gels synthesized therefrom can be used in such applications as tissue engineering, drug delivery, separation of biomolecules, and stimulus-responsive advanced materials